The naissance of optical fibers not only brings innovation to the field of communications, but also contributes to major revolutions and development in the field of sensor monitoring. The technical superiorities of an optic sensing technology like resistance to strong electromagnetic interference, low cost, and distributed monitoring promote it to be widely used in the field of safety and health monitoring such as water conservancy and civil engineering. However, due to the incomplete technology itself and the specificity of the working environment, there are still a large number of technical problems which have not been effectively resolved to apply the optical fiber sensing technology in hydraulic structure seepage monitoring (especially seepage quantity and seepage line monitoring). Although a conventional optimal design by means of optical fiber layout plans plays a certain positive role of improving the optical fiber seepage measurement accuracy and efficiency, the technical defects and deficiencies of conventional optical fiber seepage measurement cannot be fundamentally solved yet; moreover, the construction difficulty and layout cost will be significantly increased usually, which greatly limits the application and promotion of the technology in actual engineering.
When sensing optical fiber is used for seepage monitoring, an external circuit is usually needed to heat the optical fiber; for this purpose, not only the optical fiber used needs to have a heating function, but also a complete heating circuit needs to be built, which greatly increases the production cost of the optical fiber. Moreover, since it is difficult to coordinate a relationship between the external circuit and the heating optical fiber during indoor and outdoor monitoring, voltage instability or too large heating optical fiber is frequently caused, and a jacket of the optical fiber is soft or even burned in a short time therefore, which causes severe harm to operators and instruments. In addition, on-site monitoring applied to actual engineering often lacks necessary safety measures, and it is difficult to lay the heating circuits. It is more difficult and even unable to implement optical fiber laying and heating function since most of water conservancy and hydropower engineering are located in remote areas with very bad construction and operation environments. Therefore, it is urgent to fully consider the characteristics of hydraulic seepage monitoring and special working environment, focus on the production and assembly of the sensing optical fiber itself, and develop an optical fiber having an automatic control heat source specifically produced for hydraulic seepage measurement, so as to enhance the performance indicators and practical ability of the optical fiber seepage measurement technology from the source.
The present invention is just developed on the basis of the above-mentioned background and object and with reference to the problems encountered in practical engineering. The single-core arrangement of the present invention can detect structure seepage more effectively and directly, so that the application range of the present invention can be further expanded. The five-layer arrangement of the inner protective elastic layer, the heat insulation steel ring, the inner-layer filling protection ring, the elastic hard ring and the anti-seepage heat insulation hard sleeve ring increases the levels of anti-seepage and elastic buffer, and has stronger engineering suitability. The inwards depressed design of the four sides greatly increases the monitoring directions and scope of the present invention. The simple design of the drainage water storage cotton sleeve, the first filter screen and the second filter screen enhances the entire adaptation of the present invention.